Alternative Materials for the Enrichment of Biogas with Methane.

Carbonaceous adsorbents have been pointed out as promising adsorbents for the recovery of methane from its mixture with carbon dioxide, including biogas. This is because of the fact that CO2 is more strongly adsorbed and also diffuses faster compared to methane in these materials. Therefore, the present study aimed to test alternative carbonaceous materials for the gas separation process with the purpose of enriching biogas in biomethane and to compare them with the commercial one. Among them was coconut shell activated carbon (AC) as the adsorbent derived from bio-waste, rubber tire pyrolysis char (RPC) as a by-product of waste utilization technology, and carbon molecular sieve (CMS) as the commercial material. The breakthrough experiments were conducted using two mixtures, a methane-rich mixture (consisting of 75% CH4 and 25% CO2) and a carbon dioxide-rich mixture (containing 25% CH4 and 75% CO2). This investigation showed that the AC sample would be a better candidate material for the CH4/CO2 separation using a fixed-bed adsorption column than the commercial CMS sample. It is worth mentioning that due to its poorly developed micropore structure, the RPC sample exhibited limited adsorption capacity for both compounds, particularly for CO2. However, it was observed that for the methane-rich mixture, it was possible to obtain an instantaneous concentration of around 93% CH4. This indicates that there is still much potential for the use of the RPC, but this raw material needs further treatment. The Yoon-Nelson model was used to predict breakthrough curves for the experimental data. The results show that the data for the AC were best fitted with this model.

LCA and economic study on the local oxygen supply in Central Europe during the COVID-19 pandemic.

Medical oxygen is the key to survival for COVID-19 patients. To meet the pandemic-driven oxygen demand spike, local hospitals began searching for a suitable medical oxygen delivery system. Among the studies published on the impact of COVID-19 on a range of aspects, including the global economy and the environment, no study has been conducted on the environmental impact of medical oxygen supply to hospitals under epidemic conditions. In this paper the authors perform a comparative Life Cycle Assessment (LCA) to evaluate the environmental and economic impact of three scenarios (oxygen cylinders, liquid oxygen in tanks and on-site oxygen production) of local oxygen supply to hospitals in Poland. The LCA was performed according to ISO 14040 -14044 standards requirements, using the SimaPro 9.0 software. Results from the analysis showed that the Global Warming Potential (GWP) and Fine Particulate Matter Formation Potential (FPMFP) indicators for the liquid oxygen in tank scenario are the lowest and equal 265 kg CO2 eq and 0.309 kg PM2.5 eq. respectively. The greatest terrestrial acidification reductions (-1.38 kg SO2 eq) can be achieved when applying the on-site oxygen production scenario. Our findings revealed that the oxygen in cylinders scenario has the most harmful impact on the environment. The economic analysis was performed in order to compare the monthly and annual operational costs of analysed scenarios. The results show that hospitals sustain the lowest annual costs when using the on-site oxygen production scenario.